Multilayer light diffuser plate and method for manufacturing the same

ABSTRACT

A multilayer light diffuser plate and a method for manufacturing the same are disclosed. The multilayer light diffusion plate comprises a main layer and a partially-transmissive and partially-reflective layer located under the main layer. The top surface of the main layer is the light-emitting surface, and the light-incident surface is the bottom surface of the partially-transmissive and partially-reflective layer. The partially-transmissive and partially-reflective layer comprises a plurality of first base material layers and a plurality of second base material layers stacked alternately. The materials of the first and second base material layers have different refractive indices. The partially-transmissive and partially-reflective layer formed by alternately stacking the first and second base material layers with different refractive indices is arranged on the light-incident surface of the light diffuser plate by means of extrusion, which is simpler and less expensive to manufacture.

This application claims the benefit of Taiwan Patent Application SerialNo. 111118965 filed May 20, 2022, the subject matter of which isincorporated herein by reference.

BACKGROUND OF INVENTION 1. Field of the Invention

The present invention refers to a multilayer light diffuser plateapplied to a direct-type backlight module and a method for making thesame, especially refers to a multilayer light diffuser plate which isprovided with a partially-transmissive and partially-reflective layerformed by alternately stacking a plurality of first base material layersand second base material layers with different refractive indices on thelight-incident surface of the light diffuser plate.

2. Description of the Prior Art

At present, more and more liquid-crystal display (LCD) devices usedirect-type backlight modules to provide the light source of theirliquid-crystal panels. Conventional direct-type backlight modulesgenerally use a light source module equipped with light-emitting diodes(LEDs) disposed on the bottom side of the direct-type backlight modulesto provide the light required. The light emitted by the LEDs ishomogenized by a light diffuser plate and then emitted out from alight-emitting surface on the top side upward, so as to improve thebright and dark bands (MURA) phenomenon of the light-emitting surface ofthe light diffuser plate.

The conventional light diffuser plate mainly provides the lightdiffusing function in the following ways:

-   -   (1) Adding a number of tiny diffusing particles inside the light        diffuser plate. The effect of refraction, reflection or        scattering of light is achieved by the different refractive        indices of the materials of the diffusing particles and the        light diffuser plate, so as to diffuse the light. In order to        achieve a good uniform light diffusing effect, it is necessary        to increase the amount of diffusing particles added to reduce        the light transmittance, or increase the distance between the        light diffuser plate and the LED light source module; however,        these practices will reduce the light utilization rate or        increase the overall thickness of the backlight module.    -   (2) Adding a plurality of microstructures on the surface of the        light diffuser. Use surface microstructures to change the        direction of light travel, so as to provide the function of        light diffusion. Due to the use of the extrusion process, a good        transfer rate cannot be obtained, thereby reducing the effect of        the microstructures to change the direction of light.    -   (3) Printing a plurality of dots on the surface of the light        diffuser plate. The surface printing dots are used to        diffuse/shade different positions on the surface of the light        diffuser plate, thereby reducing the bright and dark bands        between the LEDs on the light emitting surface. However,        multiple processing steps are required for printing dots, and        there is an assembly alignment problem.

As can be seen from the above, in order to achieve the light diffusioneffect, the currently known light diffuser plate technologies are mainlyto add light diffusing particles to the light diffuser plate composed ofthermoplastic materials, to extrude surface microstructures by rollers,or to print dots on the surface of the light diffuser plate. However,these technologies have limited diffusion effects and have the followingdisadvantages: need to increase the thickness of the diffuser plate, orreduce the penetration rate of the diffuser plate, or increase thedistance between the LEDs and the diffuser plate, or increase the numberof steps for multiple processing and have assembly alignment problems .. . etc., and thus still need to be improved.

In the present invention, a partially-transmissive andpartially-reflective layer is arranged on the surface of the lightdiffuser plate to partially penetrate and partially reflect theintensity of the linear light source above the LEDs. In this way, thebright and dark bands between the LEDs are reduced in order to achievethe uniform light-diffusing effect. The partially-transmissive andpartially-reflective layer of the prior art can be obtained bycoating/electroplating methods, but requires subsequent processing,which is complicated and expensive. In contrast, in the presentinvention, by means of extrusion molding, the light-incident surface ofthe light diffuser plate is provided with the partially-transmissive andpartially-reflective layer by alternately stacking a plurality of firstbase material layers and second base material layers with differentrefractive indices, which can solve the problems of complicated processand high cost of conventional coating/electroplating methods for makingthe partially-transmissive and partially-reflective layer.

SUMMARY OF THE INVENTION

The primary objective of the invention is to provide a multilayer lightdiffuser plate and a method for manufacturing the same. The multilayerlight diffusion plate comprises a main layer and apartially-transmissive and partially-reflective layer. Thelight-emitting surface of the multilayer light diffusion plate is thetop surface of the main layer, and the light-incident surface is thebottom surface of the partially-transmissive and partially-reflectivelayer. The partially-transmissive and partially-reflective layer islocated under the main layer and is composed of a plurality of firstbase material layers and a plurality of second base material layersstacked alternately. The materials of the first base material layer andthe second base material layer have different refractive indices. Thelight-incident surface of the light diffuser plate is provided with thepartially-transmissive and partially-reflective layer, which canpartially penetrate and partially reflect the intensity of the linearlight source of the LED light source module below, thereby reducing thebright and dark bands (MURA) between the LEDs and achieving the effectof uniform light. In addition, the partially-transmissive andpartially-reflective layer formed by alternately stacking a plurality offirst base material layers and second base material layers withdifferent refractive indices is arranged on the light-incident surfaceof the light diffuser plate by means of extrusion, which is simpler andless expensive to manufacture.

In order to achieve the aforementioned objective, the present inventionprovides a multilayer light diffuser plate capable of being assembled ona light source module. The multilayer light diffuser plate has alight-incident surface and a light-emitting surface that are parallel toeach other. A distance between the light-incident surface and thelight-emitting surface is a thickness of the multilayer light diffuserplate. The light-incident surface is adjacent to the light sourcemodule, so that the light emitted from the light source module can enterthe multilayer light diffuser plate through the light-incident surfaceand travel substantially along a thickness direction. The multilayerlight diffuser plate comprises: a main layer and apartially-transmissive and partially-reflective layer located below themain layer. The light-emitting surface is located on a top surface ofthe main layer. The light-incident surface is located on a bottomsurface of the partially-transmissive and partially-reflective layer.Wherein, the partially-transmissive and partially-reflective layercomprises a plurality of first base material layers and a plurality ofsecond base material layers stacked alternately. At least one of theupper and lower sides of each of the first base material layers isadjacent to one of the second base material layers. In addition, atleast one of the upper and lower sides of each of the second basematerial layers is adjacent to one of the first base material layers. Amaterial constituting the first base material layers and anothermaterial constituting the second base material layers have differentrefractive indices.

In a preferred embodiment, base materials of the main layer and thepartially-transmissive and partially-reflective layer are eithernon-crystalline or semi-crystalline plasticized materials. A ratio ofthe thickness of the main layer to the thickness of thepartially-transmissive and partially-reflective layer is in the range of9:1 to 7:3. A number of stacked layers of the partially-transmissive andpartially-reflective layer, that is, the sum of the number of layers ofthe first base material layers and the second base material layers, isbetween 50 and 400 layers. A ratio of the thickness of the first basematerial layer to the thickness of the second base material layer isranged from 3:1 to 1:3.

In a preferred embodiment, the materials of the main layer and thepartially-transmissive and partially-reflective layer are respectivelyselected from one of the following: polycarbonate (PC), polystyrene(PS), polymethyl methacrylate (PMMA, commonly known as acrylic force),polyethylene (PE), polypropylene (PP), and polyethylene terephthalate(PET). The number of stacked layers of the partially-transmissive andpartially-reflective layer is between 100 and 400 layers.

In a preferred embodiment, the material of the main layer ispolycarbonate (PC); the material of the first base material layers ispolycarbonate (PC); the material of the second base material layers ispolymethyl methacrylate (PMMA). The thicknesses of the first basematerial layer and the thicknesses of the second base material layer arethe same, that is, the ratio of the thickness of each first basematerial layer to the thickness of each second base material layer 122is 1:1. The light source module is an LED light source module comprisinga plurality of light-emitting diodes (LEDs) arranged in an array. Thethickness of the multilayer light diffuser plate ranges from 1.0 mm to3.0 mm.

In a preferred embodiment, the multilayer light diffuser plate is madeby foam extrusion molding, and the main layer comprises a plurality ofmicrobubbles and a plurality of diffusing particles. A material of thediffusing particles is one of the following: calcium carbonate, silicondioxide, titanium dioxide, silicone resin microparticles, and polymethylmethacrylate microparticles. A weight percentage of the diffusingparticles in the main layer is 0.1%˜10%. The microbubbles aredistributed in the main layer; due to the difference in refractiveindices between air in the microbubbles and the material of the mainlayer, light traveling in the main layer can be refracted, reflected orscattered by the microbubbles. A weight reduction rate of themicrobubbles to the main layer is 15-25%, and an average size of themicrobubbles is between 60˜800 μm. Wherein, a calculation formula of theweight reduction rate is:

weight reduction rate (%)=(W1−W2)/W2*100%;

W1=H*(L1*L2*D);

-   -   wherein:    -   H is the average thickness of the main layer (mm);    -   L1 is the length of the main layer (mm);    -   L2 is the width of the main layer (mm);    -   D is the density of the raw material of the main layer (g/mm³);    -   W1 is the theoretical weight (g) of the main layer, that is, the        weight when the microbubbles are not included;    -   W2 is the actual weight (g) of the main layer, that is, the        actual weight of the plate body containing a plurality of the        microbubbles is actually weighed by a scale.

In a preferred embodiment, the multilayer light diffuser plate furthercomprises a quantum dot layer and a water-blocking and gas-blockinglayer. A plurality of microstructures is disposed on the light-emittingsurface of the multilayer light diffuser plate in an array form. Aplurality of convex portions and a plurality of concave portions areformed on the light-emitting surface by means of the microstructures.The concave portions are separated by the convex portions, so theconcave portions are independent and do not communicate with each other.The quantum dot layer is disposed at the concave portions on thelight-emitting surface of the light diffuser plate. A thickness of thequantum dot layer is t1, a distance from a top of the convex portions toa bottom of the concave portions is t2, wherein t1<t2. Thewater-blocking and gas-blocking layer is disposed entirely on thelight-emitting surface of the light diffuser plate and is closelyadhered to cover the plurality of convex portions and the quantum dotlayer. The quantum dot layer comprises a plurality of quantum dots. Thequantum dots are nanocrystal semiconductor materials, which are composedof II-VI, III-V or IV-VI group elements. A grain diameter of each of thequantum dots is between 2 nm and 10 nm. Wherein, the quantum dotsinclude a plurality of green quantum dots with light emissionwavelengths of 520-530 nm and a plurality of red quantum dots with lightemission wavelengths of 620-630 nm. The light source module is a bluelight LED light source module formed by a plurality of bluelight-emitting diodes (LEDs) arranged in an array.

In a preferred embodiment, the microstructures include a plurality ofN-sided pyramids, wherein N is a positive integer greater than or equalto three; t2 is between 6-200 μm; the maximum width of the convexportions is between 50-500 μm; a distance between two adjacent saidconvex portions is between 50-1000 μm. A thickness of the water-blockingand gas-blocking layer is t3, and t3 is between 5-100 μm. The blue lightLED light source module is a sub-millimeter light-emitting diode (MiniLED) array module capable of emitting blue light; a wavelength of theblue light is between 430-500 nm.

In a preferred embodiment, a plurality of said microstructures isdisposed on the light-incident surface of the multilayer light diffuserplate in an array form. A plurality of said convex portions and aplurality of said concave portions are formed on the light-incidentsurface by means of the microstructures.

In order to achieve the aforementioned objective, the present inventionprovides a method for manufacturing a multilayer light diffuser plate,comprising the following steps:

-   -   a step for inserting material, wherein at least a first base        material, a second base material, a foaming agent, and a        plurality of diffusing particles are put into a foam extrusion        molding machine from a feeding port; wherein the first base        material and the second base material have different refractive        indices;    -   a step for heating and kneading, wherein, in the foam extrusion        molding machine, the inserted materials are uniformly heated,        kneaded and foamed at a general processing temperature suitable        for polycarbonate; wherein the first base material and the        second base material are separately heated and kneaded without        mixing;    -   a step for distributing feed block, wherein, the heated and        kneaded first base material and the heated and kneaded second        base material are directed to a distributing feed block; by        using the distributing feed block, the heated and kneaded first        base material is split into a main layer and a plurality of        first base material layers, and the heated and kneaded second        base material is split into a plurality of second base material        layers, and the first base material layers and the second base        material layers are alternately stacked to form a        partially-transmissive and partially-reflective layer, and        moreover, and the partially-transmissive and        partially-reflective layer is superimposed on the main layer;    -   a step for T-Dies, wherein, through a T-die of the foam        extrusion molding machine, the uniformly kneaded, foamed and        superimposed main layer and the partially-transmissive and        partially-reflective layer from the distributing feed block are        co-extruded into a one-piece multilayer plastic plate;    -   a step for rolling, wherein, the one-piece multilayer plastic        plate is rolled and cooled through a roller module; and    -   a step for output product, wherein the cooled one-piece        multilayer plastic plate is sent out from a discharge port of        the foam extrusion molding machine as a product of multilayer        light diffuser plate;    -   wherein the multilayer light diffuser plate sent out from the        discharge port has a light-incident surface and a light-emitting        surface that are parallel to each other, and a thickness that is        perpendicular to the light-incident surface and the        light-emitting surface; in addition, the multilayer light        diffuser plate comprises the main layer and the        partially-transmissive and partially-reflective layer; the        light-emitting surface is located on a top surface of the main        layer, the partially-transmissive and partially-reflective layer        is located below the main layer, and the light-incident surface        is located on a bottom surface of the partially-transmissive and        partially-reflective layer;    -   wherein the partially-transmissive and partially-reflective        layer comprises the first base material layers and the second        base material layers stacked alternately; at least one of the        upper and lower sides of each of the first base material layers        is adjacent to one of the second base material layers; in        addition, at least one of the upper and lower sides of each of        the second base material layers is adjacent to one of the first        base material layers; a material constituting the first base        material layers and another material constituting the second        base material layers have different refractive indices.

In a preferred embodiment, wherein, in the step for rolling, the rollermodule rolls on the one-piece multilayer plastic plate in order to forma plurality of microstructures on a light-emitting surface of theone-piece multilayer plastic plate, so that the microstructures arearranged on the light-emitting surface in an array form. Themicrostructures form a plurality of convex portions and a plurality ofconcave portions on the light-emitting surface. The concave portions areseparated by the convex portions, so the concave portions areindependent and do not communicate with each other. Wherein, thefollowing steps are further included between the step for rolling andthe step for output product:

-   -   a step for coating a quantum dot layer on the concave portions        on the light-emitting surface of the multilayer light diffuser        plate by a coating process; a thickness of the quantum dot layer        is t1, a distance from a top of the convex portions to a bottom        of the concave portions is t2, wherein t1<t2; and    -   a step for sticking a water-blocking and gas-blocking layer onto        the light-emitting surface of the multilayer light diffuser        plate in order to cover the convex portions and the quantum dot        layer. Wherein, the quantum dot layer includes a plurality of        quantum dots (QD for short). The multilayer light diffuser plate        is used with a blue light submillimeter light-emitting diode        light source module comprises a plurality of blue light        submillimeter light-emitting diodes (Mini LEDs) arranged in an        array.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be specified with reference to itspreferred embodiment illustrated in the drawings, in which:

FIG. 1 is a schematic side view of a preferred embodiment of amultilayer light diffuser plate of the present invention combined withan LED light source module to form a white light backlight moduledisposed under a liquid-crystal display panel (LCD Panel);

FIG. 2 is an enlarged schematic diagram of the side view of themultilayer light diffuser plate of the present invention as shown inFIG. 1 ;

FIG. 3A and FIG. 3B are respectively an enlarged schematic side view ofanother preferred embodiment of the multilayer light diffuser plate ofthe present invention, and a schematic diagram of a three-dimensionalexplosive view of an embodiment of the multilayer light diffuser platedisposed on the LED light source module;

FIG. 4 is a partially enlarged schematic side view of yet anotherpreferred embodiment of the multilayer light diffuser plate of thepresent invention;

FIG. 5 is a flow chart of a preferred embodiment of the method formanufacturing the multilayer light diffuser plate of the presentinvention;

FIG. 6 is a curve diagram showing the brightness of the light emitted atdifferent positions among the LEDs for a light diffuser plate withdifferent numbers of layers of the partially-transmissive andpartially-reflective layer;

FIG. 7 is a curve diagram showing the brightness of the light emitted atdifferent positions among the LEDs for a light diffuser plate with apartially-transmissive and partially-reflective layer having differencethickness ratio of the alternately stacked first base material layer andsecond base material layer;

FIG. 8 is a curve diagram showing the transmittance of thepartially-transmissive and partially-reflective layer at different lightwavelengths according to the light diffuser plate samples A, B, C, and Dwhich are furnished with the partially-transmissive andpartially-reflective layer of the present invention; and

FIG. 9 is a comparison diagram of the tastes of samples A, B, C and Dshown in FIG. 8 .

DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention refers to a multilayer light diffuser plate and amethod for manufacturing the same. The multilayer light diffusion platecomprises a main layer and a partially-transmissive andpartially-reflective layer. The light-emitting surface of the multilayerlight diffusion plate is the top surface of the main layer, and thelight-incident surface is the bottom surface of thepartially-transmissive and partially-reflective layer. Thepartially-transmissive and partially-reflective layer is located underthe main layer and is composed of a plurality of first base materiallayers and a plurality of second base material layers stackedalternately. The materials of the first base material layer and thesecond base material layer have different refractive indices. Thelight-incident surface of the light diffuser plate is provided with thepartially-transmissive and partially-reflective layer, which canpartially penetrate and partially reflect the intensity of the linearlight source of the LED light source module below, thereby reducing thebright and dark bands (MURA) between the LEDs and achieving the effectof uniform light. In addition, the partially-transmissive andpartially-reflective layer formed by alternately stacking a plurality offirst base material layers and second base material layers withdifferent refractive indices is arranged on the light-incident surfaceof the light diffuser plate by means of extrusion, which is simpler andless expensive to manufacture.

In order to more clearly describe the quantum dot light diffuser plateand its manufacturing method proposed by the present invention, thefollowing will be described in detail with the accompanying drawings.

Please refer to FIG. 1 and FIG. 2 . In which, FIG. 1 is a schematic sideview of a preferred embodiment of a multilayer light diffuser plate ofthe present invention combined with an LED light source module to form awhite light backlight module disposed under a liquid-crystal displaypanel (LCD Panel); FIG. 2 is an enlarged schematic diagram of the sideview of the multilayer light diffuser plate of the present invention asshown in FIG. 1 .

As shown in FIG. 1 and FIG. 2 , The multilayer light diffuser plate 10,the LED (light-emitting diode) light source module located under themultilayer light diffuser plate 10, and the liquid-crystal display panel93 located above the multilayer light diffuser plate 10 form an LCDdisplay module. The combination of the multilayer light diffuser plate10 and the LED light source module located below forms a white lightbacklight module for providing white light to the liquid-crystal displaypanel 93 located above, so it is a direct-type backlight module. Themultilayer light diffuser plate 10 mainly provides the functions ofconverting the light emitted by the LED light source module into whitelight, making the light output uniform, or/and enhancing the color gamutof the light output. In the present invention, The LED light sourcemodule is a sub-millimeter light-emitting diode (Mini LED) array modulecapable of emitting white light or blue light, which comprises a circuitboard 91 and a plurality of sub-millimeter light-emitting diodes (LEDs)92 arranged in an array form on the upper surface of the circuit board91. In the present embodiment shown in FIG. 1 and FIG. 2 , the LED lightsource module comprises a plurality of white light sub-millimeterlight-emitting diodes 92. However, in another embodiment of the presentinvention, which will be described later, the LED light source modulecomprises a plurality of blue light sub-millimeter light-emitting diodes92; wherein, the wavelength of the blue light emitted by each of thesub-millimeter light-emitting diodes 92 is between 430-500 nm, and thegrain size thereof is between about 100-200 μm.

The multilayer light diffuser plate 10 has a light-incident surface 120and a light-emitting surface 111 that are parallel to each other with arelatively large length and width, and a relatively small thickness thatis perpendicular to the light-incident surface 120 and thelight-emitting surface 111. The light-incident surface 120 is adjacentto or near to the LED light source module, so that the light emittedfrom the LED light source module upwards can enter the multilayer lightdiffuser plate 10 through the light-incident surface 120, and travelsubstantially along the thickness direction, and then emit upward outfrom the light-emitting surface 111.

The multilayer light diffuser plate 10 comprises a main layer 11 and apartially-transmissive and partially-reflective layer 12. Thelight-emitting surface 111 is located on a top surface of the main layer11. The partially-transmissive and partially-reflective layer 12 islocated below the main layer 11, and the light-incident surface 120 islocated on a bottom surface of the partially-transmissive andpartially-reflective layer 12. As shown in FIG. 2 , thepartially-transmissive and partially-reflective layer 12 is composed ofa plurality of first base material layers 121 and a plurality of secondbase material layers 122 stacked alternately. At least one of the upperand lower sides of each of the first base material layers 121 isadjacent to one of the second base material layers 122; in addition, atleast one of the upper and lower sides of each of the second basematerial layers 122 is adjacent to one of the first base material layers121. Materials constituting the first base material layers 121 and thesecond base material layers 122 have different refractive indices. Thatis, the refractive index of the first base material layers 121 and therefractive index of the second base material layers 122 are different.

The base materials of the main layer 11 and the partially-transmissiveand partially-reflective layer 12 of the multilayer light diffuser plate10 of the present invention can be non-crystalline or semi-crystallineplasticized materials, for example: polycarbonate (PC), polystyrene(PS), polymethyl methacrylate (PMMA, commonly known as acrylic),polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET),or a copolymer of any of the foregoing materials. The applicable rangeof the thickness of the multilayer light diffuser plate 10 is 1.0 mm˜3.0mm, and the preferred range of the thickness of the multilayer lightdiffuser plate 10 is 1.2 mm˜2.0 mm. The ratio of the thickness of themain layer 11 to the partially-transmissive and partially-reflectivelayer 12 is in the range of 9:1 to 7:3. The number of stacked layers ofthe partially-transmissive and partially-reflective layer 12, that is,the sum of the number of layers of the first base material layers 121and the second base material layers 122, can be between 50 and 400layers; however, in the preferred embodiment, the number of stackedlayers of the partially-transmissive and partially-reflective layer 12is between 100 and 400 layers. The applicable range of the ratio of thethickness of the first base material layer 121 to the thickness of thesecond base material layer 122 is ranged from 3:1 to 1:3. In thisembodiment, the material of the main layer 11 is polycarbonate (PC); thematerial of the first base material layers 121 is polycarbonate (PC);the material of the second base material layers 122 is polymethylmethacrylate (PMMA). In the best embodiment of the present invention,the thicknesses of the first base material layer 121 and the thicknessesof the second base material layer 122 are the same, that is, the ratioof the thickness of each first base material layer 121 to the thicknessof each second base material layer 122 is approximately 1:1. Since thematerials of the first base material layers 121 and the second basematerial layers 122 have different refractive indices, therefore, whenone hundred or more layers of the first base material layers 121 and thesecond base material layers 122 are alternately stacked, the light fromthe light source module below can be partially penetrated and partiallyreflected by the stacked first and second base material layers 121, 122.With the light reflecting layer disposed on the upper surface of thecircuit board 91, the light reflected downward by thepartially-transmissive and partially-reflective layer 12 can bereflected again and directed towards the light incident surface 120 ofthe partially-transmissive and partially-reflective layer 12, so as toachieve the effect of uniform light and reduce the phenomenon of brightand dark bands (MURA).

In the other embodiments of the present invention described below, sincethe structures, materials and functions of most of the elements are thesame or similar to the foregoing embodiments, the same or similarelements will be given the same element names and numbers, and theirdetails will not be repeated.

Please refer to FIG. 3A and FIG. 3B, which are respectively an enlargedschematic side view of another preferred embodiment of the multilayerlight diffuser plate of the present invention, and a schematic diagramof a three-dimensional explosive view of an embodiment of the multilayerlight diffuser plate disposed on the LED light source module.

As shown in FIG. 3A and FIG. 3B, another preferred embodiment of themultilayer light diffuser plate 10 of the present invention alsocomprises: a main layer 11, a light-emitting surface 111 located on thetop surface of the main layer 11, a partially-transmissive andpartially-reflective layer 12, and a light incident surface 120 locatedon the bottom surface of the partially-transmissive andpartially-reflective layer 12. The light incident surface 120 of themultilayer light diffuser plate 10 is also adjacent to or near to thelight-emitting diodes 92 of the LED light source module. Thepartially-transmissive and partially-reflective layer 12 also includesat least 50 or more layers (preferably at least 100 or more layers)alternately stacked first base material layers 121 and second basematerial layers 122. The difference between the present preferredembodiment and the embodiments shown in the aforementioned FIG. 1 andFIG. 2 is that, the multilayer light diffuser plate 10 of the presentpreferred embodiment shown in FIG. 3A and FIG. 3B further includes thefollowing technical contents and features.

In this embodiment, the multilayer light diffuser plate 10 is made byfoam extrusion molding, and the main layer 11 comprises a plurality ofmicrobubbles 113 and a plurality of diffusing particles 114. Thematerial of the plurality of diffusing particles 114 is one of thefollowing: calcium carbonate, silicon dioxide, titanium dioxide,silicone resin microparticles, and polymethyl methacrylatemicroparticles. The diffusing particles 114 and the main layer 111 havedifferent refractive indices, so that the light traveling in the mainlayer 11 can be refracted, reflected or scattered by the diffusingparticles 114, so as to improve the effect of uniform light output. Theweight percentage of the plurality of diffusing particles 114 in themain layer 11 is 0.1%˜10%. A plurality of the microbubbles 113 aredistributed in the main layer 11. Due to the difference in refractiveindices between the air in the microbubbles 113 and the material of themain layer 11, the light traveling in the main layer 11 can berefracted, reflected or scattered by the microbubbles 113, so as toimprove the effect of uniform light output.

In this embodiment, the preferred range of the weight reduction rate ofthe plurality of microbubbles 113 to the main layer 11 is 15-25%, andthe average size of the microbubbles 113 is between 60˜800 μm. Wherein,the calculation formula of the weight reduction rate is:

weight reduction rate (%)=(W1−W2)/W2*100%;

W1=H*(L1*L2*D);

-   -   wherein:    -   H is the average thickness of the main layer (mm);    -   L1 is the length of the main layer (mm);    -   L2 is the width of the main layer (mm);    -   D is the density of the raw material of the main layer (g/mm³);    -   W1 is the theoretical weight (g) of the main layer, that is, the        weight when the microbubbles are not included;    -   W2 is the actual weight (g) of the main layer, that is, the        actual weight of the plate body containing a plurality of the        microbubbles is actually weighed by a scale.

In this embodiment, a plurality of the microbubbles 113 are generated byadding a foaming agent and a nucleating agent in an appropriate amountduring the foam extrusion molding process of the main layer 11. In thepresent invention, the foaming agent can be selected from commerciallyavailable conventional high-temperature foaming agents, such as (but notlimited to): 5-Phenyl-1H-tetrazole (5-PT) or azodicarbonic acid(Azodicarbonamide) . . . etc. The nucleating agent comprises at leastone of the following: calcium carbonate, silicon dioxide, calcium oxide.The practical range of the weight percentage of the added nucleatingagent is 0.01%-5%, but the preferred range is 0.1%-0.5%. The weightreduction rate of the microbubbles 113 can be controlled by the amountof the foaming agent added, and the control method of the bubble size ofthe microbubbles 113 can be the addition of the nucleating agent and theadjustment of the process temperature. According to the content of themicrobubbles 113 in the main layer 11 described in this embodiment, thatis, the weight reduction rate is between 15-25% and the size is between60-800 μm, a relatively optimal uniform light extraction effect can beachieved.

In this embodiment, the light source module is a blue light LED lightsource module formed by including a plurality of blue light-emittingdiodes (LEDs) 92 arranged in an array on a circuit board 91. Moreover,the multilayer light diffuser plate 10 further comprises a quantum dotlayer 13, a water-blocking and gas-blocking layer 14, and a plurality ofmicrostructures 112.

As shown in FIG. 3A and FIG. 3B, a plurality of microstructures 112 aredisposed on the light-emitting surface 111 of the multilayer lightdiffuser plate 10 in an array form. A plurality of the microstructures112 are disposed on the top surface of the main layer 11 in an arrayform, and a plurality of convex portions and a plurality of concaveportions are formed on the top surface of the main layer 11 by means ofthe microstructures 112. The plurality of the concave portions isseparated by the plurality of the convex portions, so the concaveportions are independent and do not communicate with each other. Thequantum dot layer 13 is disposed at the plurality of concave portions onthe top surface (light-emitting surface) of the main layer 11 of thelight diffuser plate 10 in such a manner that, the quantum dot layer 13is not provided at the tops of the plurality of convex portions. Thethickness of the quantum dot layer 13 is t1, the distance from a top ofthe convex portions to a bottom of the concave portions is t2, whereint1<t2. In other words, the height t2 of the convex portion of themicrostructure 112 is larger than the thickness t1 of the quantum dotlayer 13. The separated portions of the quantum dot layer 13 located indifferent concave portions are not connected to each other. Thewater-blocking and gas-blocking layer 14 is disposed on the entire uppersurface of the light-emitting surface 111 of the light diffuser plate 10and is closely adhered to cover the plurality of convex portions and theseparated portions of the quantum dot layer 13. The water-blocking andgas-blocking layer 14 can isolate and avoid the external moisture andoxygen from invading the upper surface of the separated portions of thequantum dot layer 13. The thickness of the water-blocking andgas-blocking layer 14 is t3. The water-blocking and gas-blocking layer14 can be selected from existing commercially available water-blockingand gas-blocking films, which is directly attached on the convexportions of the microstructures 112 and quantum dot layer 13 on the topsurface of the light diffuser plate 10. The distance between twoadjacent convex portions is d2.

In the present invention, the microstructures 112 include a plurality ofN-sided pyramids, wherein N is a positive integer greater than or equalto three. In addition, the microstructures can be composed of a singleshape of pyramid, or a combination of two or more different shapes ofpyramids. The shape of the pyramid varies with the shape of its bottom,and the name is different, and it depends on the polygon of the bottom.For example, a pyramid with a triangular bottom is called a triangularpyramid, a pyramid with a square bottom is called a square pyramid, etc.A pyramid with an N-sided bottom as its base has N+1 vertices, N+1faces, and 2N edges. The dual polyhedron of a pyramid is a pyramid ofthe same shape, for example, the dual polyhedron of a square pyramid isan inverted square pyramid. As shown in FIG. 3B, each one of themicrostructures 112 presents a quadrangular pyramid (N=4) at its bottomside, that is, a square pyramid or a pyramid-shaped pyramid, in a topview. In this embodiment, the applicable range of the thickness t1 ofthe quantum dot layer 13 is 5-150 μm, but the preferred implementationrange of t1 is 10-40 μm. The applicable range of the distance t2 betweenthe tops of the convex portions and the bottoms of the concave portions(or the height of the convex portions) is 6-200 μm, but the preferredimplementation range of t2 is 25-50 μm. In addition, t1<t2. Theapplicable range of the thickness t3 of the water-blocking andgas-blocking layer 14 is 5-100 μm, but the preferred range of t3 is10-30 μm. The maximum width of the convex portions is between 50-500 μm.The applicable range of the distance d2 between the two adjacent convexportions is between 50-1000 μm, but the preferred implementation rangeof d2 is 250-500 μm. The blue LED light source module is asub-millimeter light-emitting diode (Mini LED) array module capable ofemitting blue light; the wavelength of the blue light is between 430-500nm.

In this embodiment, the quantum dot layer 13 comprises a plurality ofquantum dots 131 (QD for short). The quantum dots 131 can be selectedfrom existing commercially available nanocrystal semiconductormaterials, which are composed of II-VI, III-V or IV-VI group elements.The grain diameter of each of the quantum dots 131 is between 2 nm and10 nm. Wherein, the light emission wavelengths of the plurality ofquantum dots 131 in the quantum dot layer 13 may be between 490 nm and650 nm. In this embodiment, the plurality of quantum dots 131 include aplurality of green quantum dots with light emission wavelengths of520-530 nm and a plurality of red quantum dots with light emissionwavelengths of 620-630 nm. The blue light emitted upward by thelight-emitting elements 92 (preferably blue Mini LEDs) can be mixed intowhite light after passing through the quantum dot layer 13 and emittedupward from the light-emitting surface 111 of the light diffuser plate10. The quantum dot layer 13 needs uniform blue light intensity toconvert red/green light and mix them into uniform white light. Becausethe light intensity in the surrounding area of the LCD display module islower than the light intensity of the central area, it is easy to haveinsufficient red/green light conversion and thus result in thephenomenon of blue light at the surrounding area of the LCD displaymodule. The multilayer light diffuser plate 10 of the present inventionis formed by foam extrusion molding. The main layer 111 of themultilayer light diffuser plate 10 includes a plurality of microbubbles113 and diffusing particles 114, the light-emitting surface 111 isarranged with a plurality of microstructures 112, and the light-incidentsurface 120 is provided with a unique partially-transmissive andpartially-reflective layer 12; such that, the multilayer light diffuserplate 10 can provide better light diffusion, improve light intensity inthe area around the display, and avoid the phenomenon of blue light andbright and dark bands (MURA).

Please refer to FIG. 4 , which is a partially enlarged schematic sideview of yet another preferred embodiment of the multilayer lightdiffuser plate of the present invention. As shown in FIG. 4 , themultilayer light diffuser plate 10 of this preferred embodiment alsoincludes: a main layer 11, a light-emitting surface 111 located on thetop surface of the main layer 11, a partially-transmissive andpartially-reflective layer 12, and a light-incident surface 120 locatedon the bottom surface of the light incident surface 12. Thepartially-transmissive and partially-reflective layer 12 also includesat least 50 or more (preferably at least 100 or more) alternatelystacked first base material layers 121 and second base material layers122. The difference between the present preferred embodiment and theembodiment previously shown in FIG. 1 and FIG. 2 is that, in the presentpreferred embodiment shown in FIG. 4 , both the light-incident surface120 and the light-emitting surface 111 of the multilayer light diffuserplate 10 are furnished with a plurality of the microstructures 112. Themicrostructures 112 are arranged on both the light-incident surface 120and the light-emitting surface 111 of the multilayer light diffuserplate 10 in the form of an array. The microstructures 112 respectivelyform a plurality of convex portions and a plurality of concave portionson both the light-incident surface 120 and the light-emitting surface111 of the multilayer light diffuser plate 10. In addition, the mainlayer 111 includes a plurality of microbubbles 113 and a plurality ofdiffusing particles 114. The partially-transmissive andpartially-reflective layer 12 located on the light-incident surface 120co-works with the microbubbles 113 and diffusing particles 114 containedin the main layer 111, and the microstructures 112 disposed on both thelight-incident surface 120 and the light-emitting surface 111, which canprovide relatively optimal light diffusion effect.

When the multilayer light diffuser plate 10 of the present invention isused with a white LED light source module, or, although it is used witha blue LED light source module, but an additional quantum dot film isprovided or a light color conversion material or a phosphor powder isadded to the main layer, the multilayer light diffuser plate 10 itselfdoes not need to be provided with a quantum dot layer.

Please refer to FIG. 5 , which is a flow chart of a preferred embodimentof the method for manufacturing the multilayer light diffuser plate ofthe present invention. In this embodiment, the manufacturing process ofthe multilayer light diffuser plate comprises the following steps:

-   -   Step 21: insert material; at least a first base material, a        second base material, a foaming agent, and a plurality of        diffusing particles are put into a foam extrusion molding        machine from a feeding port in order to manufacture a multilayer        light diffuser plate; wherein the first base material and the        second base material have different refractive indices;    -   Step 22: heating and kneading; in the foam extrusion molding        machine, the inserted materials are uniformly heated, kneaded        and foamed at a general processing temperature suitable for        polycarbonate; wherein the first base material and the second        base material are separately heated and kneaded without mixing;    -   Step 23: distributing feed block; the heated and kneaded first        base material and the heated and kneaded second base material        are directed to a distributing feed block; by using the        distributing feed block, the heated and kneaded first base        material is split into a main layer and a plurality of first        base material layers, and the heated and kneaded second base        material is split into a plurality of second base material        layers, and a plurality of the first base material layers and a        plurality of the second base material layers are alternately        stacked to form a partially-transmissive and        partially-reflective layer, and moreover, and the        partially-transmissive and partially-reflective layer is        superimposed on the main layer;    -   Step 24: T-Dies; through a T-die of the foam extrusion molding        machine, the uniformly kneaded, foamed and superimposed main        layer and the partially-transmissive and partially-reflective        layer from the distributing feed block are co-extruded into a        one-piece multilayer plastic plate;    -   Step 25: rolling; the one-piece multilayer plastic plate is        rolled and cooled through a roller module; in the rolling step        25, the roller module rolls on the one-piece multilayer plastic        plate in order to form a plurality of microstructures on a        light-emitting surface of the multilayer light diffuser plate,        so that the microstructures are arranged on the light-emitting        surface of the multilayer light diffuser plate in an array form;        the microstructures form a plurality of convex portions and a        plurality of concave portions on the light-emitting surface of        the multilayer light diffuser plate; a plurality of the concave        portions are separated by a plurality of the convex portions, so        the plurality of the concave portions are independent and do not        communicate with each other;    -   Step 26: output product; the cooled multilayer light diffuser        plate is sent out from a discharge port of the foam extrusion        molding machine.

Wherein, the multilayer light diffuser plate sent out from the dischargeport has a light-incident surface and a light-emitting surface that areparallel to each other, and a thickness that is perpendicular to thelight-incident surface and the light-emitting surface; in addition, themultilayer light diffuser plate comprises the main layer and thepartially-transmissive and partially-reflective layer; thelight-emitting surface is located on a top surface of the main layer,the partially-transmissive and partially-reflective layer is locatedbelow the main layer, and the light-incident surface is located on abottom surface of the partially-transmissive and partially-reflectivelayer. The partially-transmissive and partially-reflective layer iscomposed of a plurality of the first base material layers and aplurality of the second base material layers stacked alternately. Atleast one of the upper and lower sides of each of the first basematerial layers is adjacent to one of the second base material layers;in addition, at least one of the upper and lower sides of each of thesecond base material layers is adjacent to one of the first basematerial layers. Materials constituting the first base material layersand the second base material layers have different refractive indices.That is, the refractive index of the first base material layers and therefractive index of the second base material layers are different.

In a preferred embodiment, the following steps are further includedbetween the rolling step 25 and the output product step 26: coating aquantum dot layer on a plurality of the concave portions on thelight-emitting surface of the multilayer light diffuser plate by acoating process. The thickness of the quantum dot layer is t1, thedistance from a top of the convex portions to a bottom of the concaveportions is t2, wherein t1<t2. In other words, the height t2 of theconvex portion of the microstructure is larger than the thickness t1 ofthe quantum dot layer. The separated portions of the quantum dot layerlocated in different concave portions are not connected to each other.And then, through a sticking process, a water-blocking and gas-blockinglayer is attached to the light-emitting surface of the multilayer lightdiffuser plate and covers the convex portions and the quantum dot layer.Wherein, the quantum dot layer includes a plurality of quantum dots (QDfor short). The multilayer light diffuser plate is used with a bluelight source module. The blue light source module is a blue lightsubmillimeter light-emitting diode light source module composed of aplurality of blue light submillimeter light-emitting diodes (Mini LEDs)arranged in an array.

The applicant has prepared several different samples of light diffuserplates (that is, Comparative Examples 1 to 3 of the prior art andEmbodiment 1 of the present invention as shown in Table 1 below);wherein each of them is applied with different light diffusiontechnologies such as “diffusing particles”, “surface microstructures”and/or “partially-transmissive and partially-reflective layer”,respectively. Then, the applicant observed the optical effects such as“light diffuser plate transmittance”, “brightness” and “optical taste (5is the best, 1 is the lowest)” of each light diffuser plate samplesassembled with a light source module. The test results are listed inTable 1 below. Among them, only the light diffuser plate of Embodiment 1has employed with the technology of providing a partially-transmissiveand partially-reflective layer on the light-incident surface of thelight diffuser plate according to the present invention, and the otherComparative Examples 1 to 3 do not have the partially-transmissive andpartially-reflective layer. It is notable that, the specific structureof the light diffuser plate of Embodiment 1 can be directly referred tothe structure of the multilayer light diffuser plate 10 shown in FIG. 1and FIG. 2 ; wherein, the multilayer light diffuser plate does notcontain “diffusing particles” and “surface microstructures”. As can beseen from Table 1, because Embodiment 1 uses the technology andstructure of the present invention of “arranging apartially-transmissive and partially-reflective layer on thelight-incident surface of the light diffuser plate”, so even ifEmbodiment 1 does not include “diffusing particles” and “surfacemicrostructures”, Embodiment 1 still has the relatively best opticalperformance of brightness and taste, and relatively better opticalperformance of transmittance, in comparison with other light diffuserplates that only use “diffusing particles” or/and “surfacemicrostructures”

(Comparative Examples 1 to 3).

TABLE 1 The comparison table of optical performances between the lightdiffuser plate provided with a partially-transmissive and partially-reflective layer of the present invention and other conventional lightdiffusing technologies. Distance Amount With or trans- between ofwithout mittance diffuser diffusing surface of plate particles micro-diffuser and Bright- added structures plate LEDs ness Taste Comparative5% NA 45% 2 mm 100% 2 Example 1 Comparative NA YES 75% 2 mm 110% 3Example 2 Comparative 5% YES 44% 2 mm 108% 3 Example 3 Embodiment NA NA47% 2 mm 110% 4 1 NA = not any

Please refer to the following Table 2, which is a comparison tablesimilar to Table 1, except that, in addition to the Embodiment 1 that isprovided with a partially-transmissive and partially-reflective layer onthe light-incident surface of the light diffuser plate without diffusingparticles nor surface microstructures, Embodiment 2 and Embodiment 3 arefurther included in the Table 2; moreover, in the test, the distancebetween the diffuser plate and the LEDs is reduced to 0 mm. Among them,in Embodiment 2, a partially-transmissive and partially-reflective layeris also provided on the light-incident surface of the light diffuserplate, and 2% diffusing particles are added, but no surfacemicrostructure is provided. In Embodiment 3, a partially-transmissiveand partially-reflective layer is also arranged on the light-incidentsurface of the light diffuser plate, and 2% diffusion particles areadded, and a plurality of surface microstructures are also arranged.Comparative Examples 1 to 3 in Table 2 have the same structures as thoseshown in Table 1. It can be seen from Table 2 that, not only the opticalperformances (brightness and taste) of Embodiments 1 to 3 of the lightdiffuser plate using the technology of applying thepartially-transmissive and partially-reflective layer on thelight-incident surface of the present invention are significantly betterthan that of Comparative Examples 1 to 3 that does not use thetechnology of the present invention, but also that, since Embodiment 3is further applied with the technologies of adding 2% diffusingparticles and furnishing surface microstructures, the opticalperformances of Embodiment 3 (brightness and taste) is the best of allsamples, and the optical performance of transmittance of Embodiment 3 isalso relatively good. In addition, it can be found from Table 2 that,when the distance between the diffuser plate and the LEDs is reduced to0 mm, the taste of Comparative Examples 1 to 3, which do not use thetechnology of applying the partially-transmissive andpartially-reflective layer on the light-incident surface of the presentinvention, will be greatly reduced; that is, the MURA problem willbecome very serious. In contrast, the decrease in taste of Embodiments 1to 3 is not so obvious, and it can be seen that the technology of thepresent invention can provide a relatively optimal light diffusioneffect. In particular, for the

Embodiments 3 of the present invention (in addition to the applicationof the partially-transmissive and partially-reflective layer on thelight-incident surface, the addition of 2% diffusing particles and thesurface microstructures are also provided), even when the bottom surfaceof the diffuser plate is directly contacting the LEDs (that is, thedistance between the diffuser plate and the LEDs is 0 mm), good opticalperformances of brightness, taste, and transmittance can still beachieved; such structure can greatly reduce the overall thickness of thedirect-type backlight module, making the product thinner and moreconvenient to carry.

TABLE 2 The comparison table of optical performances between the lightdiffuser plate provided with a partially-transmissive andpartially-reflective layer of the present invention and otherconventional light diffusing technologies. Distance Amount With ortrans- between of without mittance diffuser diffusing surface of plateparticles micro- diffuser and Bright- added structures plate LEDs nessTaste Comparative 5% NA 45% 0 mm 100% 1 Example 1 Comparative NA YES 75%0 mm 110% 1 Example 2 Comparative 5% YES 44% 0 mm 108% 1 Example 3Embodiment NA NA 47% 0 mm 110% 3 1 Embodiment 2% NA 47% 0mm 110% 4 2Embodiment 2% YES 50% 0 mm 115% 4 3 NA = not any

Please refer to the following Table 3, which is a comparison tablesimilar to Table 1 and Table 2, except that, the newly includedEmbodiment 7 and Embodiment 8 are compared with the aforementionedComparative Example 3 in Table 3. Among them, in Embodiment 7, inaddition to providing a partially-transmissive and partially-reflectivelayer on the light-incident surface of the light diffuser plate, foamingwas performed during the heating and kneading process of the main layerof the light diffuser plate to generate microbubbles. In Embodiment 8,in addition to providing a partially-transmissive andpartially-reflective layer on the light-incident surface of the lightdiffuser plate, and performing foaming process to generate microbubblesin the main layer, the main layer is further added with light colorconversion materials that can convert blue light to white light. It canbe seen from Table 3 that, the samples of Embodiment 7 and Embodiment 8include microbubbles and light color conversion materials in the mainlayer of the light diffuser plate, which will only slightly reduce thelight transmittance and brightness, but can further improve the taste.Even when the bottom surface of the diffuser plate is directlycontacting the LEDs (that is, the distance between the diffuser plateand the LEDs is 0 mm), good optical performances of brightness and tasteas well as acceptable transmittance can still be achieved; suchstructure can greatly reduce the overall thickness of the direct-typebacklight module, making the product thinner and more convenient tocarry.

TABLE 3 The comparison table of optical performances between the lightdiffuser plate provided with a partially-transmissive andpartially-reflective layer, foaming microbubbles and color conversionmaterials of the present invention and other conventional lightdiffusing technologies. Distance Amount With or trans- between ofwithout mittance diffuser diffusing surface of plate particles micro-diffuser and Bright- added structures plate LEDs ness Taste Comparative5% YES 44% 0 mm 108% 1 Example 3 Embodiment foaming NA 38% 0 mm 110% 5 7Embodiment foaming + YES 40% 0 mm 115% 5 8 color conversion NA = not any

Please refer to FIG. 6 , which is a curve diagram showing the brightnessof the light emitted at different positions among the LEDs for a lightdiffuser plate with different numbers of layers of thepartially-transmissive and partially-reflective layer. Wherein, thehorizontal axis of FIG. 6 is the position of the light diffuser plate inthe horizontal direction (the unit of distance is cm), and the verticalaxis is the illuminance value (the unit is lux). It can be seen fromFIG. 6 that, the conventional diffuser plate does not have apartially-transmissive and partially-reflective layer on thelight-incident surface, so the phenomenon of bright and dark bands(MURA) is extremely serious. When the light-incident surface of thediffuser plate is provided with a partially-transmissive andpartially-reflective layer, the number of layers stacked with differentrefractive indices will affect its anti-MURA performance; as shown inFIG. 6 , when the number of layers is only 25 layers, the LED bright anddark bands are still slightly obvious, but when the number of layersreaches 100 layers or above, the difference between bright and darkbands can be evened out.

Please refer to FIG. 7 , which is a curve diagram showing the brightnessof the light emitted at different positions among the LEDs for a lightdiffuser plate with a partially-transmissive and partially-reflectivelayer having difference thickness ratio of the alternately stacked firstbase material layer and second base material layer. Wherein, thehorizontal axis of FIG. 7 is the position of the light diffuser plate inthe horizontal direction (the unit of distance is cm), and the verticalaxis is the illuminance value (the unit is lux). It can be seen fromFIG. 7 that, when the thickness ratio of the first base material layerand the second base material layer is 1:1, a relatively optimal uniformlight effect can be obtained.

Please refer to FIG. 8 and FIG. 9 . Wherein, FIG. 8 is a curve diagramshowing the transmittance of the partially-transmissive andpartially-reflective layer at different light wavelengths according tothe light diffuser plate samples A, B, C, and D which are furnished withthe partially-transmissive and partially-reflective layer of the presentinvention. FIG. 9 is a comparison diagram of the tastes of samples A, B,C and D shown in FIG. 8 . Wherein, the horizontal axis of FIG. 8 is thelight wavelength (unit is nm), and the vertical axis is thetransmittance (%). It can be seen from FIG. 8 and FIG. 9 that, for lightdiffuser plates furnished with a partially-transmissive andpartially-reflective layer, when their transmittance for 400 nm is inthe range of 30˜60% and their reflectance is in the range of 60˜30%,that is, the sample B and sample C, they will have the least obviousMURA problem, so they can get the best taste.

While the present invention has been particularly shown and describedwith reference to a preferred embodiment, it will be understood by thoseskilled in the art that various changes in form and detail may bewithout departing from the spirit and scope of the present invention.

1. A multilayer light diffuser plate capable of being assembled on alight source module; the multilayer light diffuser plate having alight-incident surface and a light-emitting surface that are parallel toeach other; a distance between the light-incident surface and thelight-emitting surface being a thickness of the multilayer lightdiffuser plate; the light-incident surface being adjacent to the lightsource module, so that the light emitted from the light source modulecan enter the multilayer light diffuser plate through the light-incidentsurface and travel substantially along a thickness direction; themultilayer light diffuser plate comprising: a main layer, thelight-emitting surface being located on a top surface of the main layer;and a partially-transmissive and partially-reflective layer, locatedbelow the main layer; the light-incident surface is located on a bottomsurface of the partially-transmissive and partially-reflective layer;wherein, the partially-transmissive and partially-reflective layercomprises a plurality of first base material layers and a plurality ofsecond base material layers stacked alternately; at least one of theupper and lower sides of each of the first base material layers isadjacent to one of the second base material layers; in addition, atleast one of the upper and lower sides of each of the second basematerial layers is adjacent to one of the first base material layers; amaterial constituting the first base material layers and anothermaterial constituting the second base material layers have differentrefractive indices; wherein: base materials of the main layer and thepartially-transmissive and partially-reflective layer are eithernon-crystalline or semi-crystalline plasticized materials; a ratio ofthe thickness of the main layer to the thickness of thepartially-transmissive and partially-reflective layer is in the range of9:1 to 7:3; a number of stacked layers of the partially-transmissive andpartially-reflective layer, that is, the sum of the number of layers ofthe first base material layers and the second base material layers, isbetween 50 and 400 layers; a ratio of the thickness of the first basematerial layer to the thickness of the second base material layer isranged from 3:1 to 1:3; wherein: the multilayer light diffuser platefurther comprises a quantum dot layer and a water-blocking andgas-blocking layer; a plurality of microstructures is disposed on thelight-emitting surface of the multilayer light diffuser plate in anarray form; a plurality of convex portions and a plurality of concaveportions are formed on the light-emitting surface by means of themicrostructures; the concave portions are separated by the convexportions, so the concave portions are independent and do not communicatewith each other; the quantum dot layer is disposed at the concaveportions on the light-emitting surface of the light diffuser plate; athickness of the quantum dot layer is t1, a distance from a top of theconvex portions to a bottom of the concave portions is t2, whereint1<t2; the water-blocking and gas-blocking layer is disposed entirely onthe light-emitting surface of the light diffuser plate and is closelyadhered to cover the plurality of convex portions and the quantum dotlayer; the quantum dot layer comprises a plurality of quantum dots; thequantum dots are nanocrystal semiconductor materials, which are composedof II-VI, III-V or IV-VI group elements; a grain diameter of each of thequantum dots is between 2 nm and 10 nm; wherein, the quantum dotsinclude a plurality of green quantum dots with light emissionwavelengths of 520-530 nm and a plurality of red quantum dots with lightemission wavelengths of 620-630 nm; the light source module is a bluelight LED light source module formed by a plurality of bluelight-emitting diodes (LEDs) arranged in an array.
 2. (canceled)
 3. Themultilayer light diffuser plate of claim 1, wherein, the materials ofthe main layer and the partially-transmissive and partially-reflectivelayer are respectively selected from one of the following: polycarbonate(PC), polystyrene (PS), polymethyl methacrylate (PMMA, commonly known asacrylic force), polyethylene (PE), polypropylene (PP), and polyethyleneterephthalate (PET); the number of stacked layers of thepartially-transmissive and partially-reflective layer is between 100 and400 layers.
 4. The multilayer light diffuser plate of claim 3, wherein,the material of the main layer is polycarbonate (PC); the material ofthe first base material layers is polycarbonate (PC); the material ofthe second base material layers is polymethyl methacrylate (PMMA); thethicknesses of the first base material layer and the thicknesses of thesecond base material layer are the same, that is, the ratio of thethickness of each first base material layer to the thickness of eachsecond base material layer 122 is 1:1; the light source module is an LEDlight source module comprising a plurality of light-emitting diodes(LEDs) arranged in an array; the thickness of the multilayer lightdiffuser plate ranges from 1.0 mm to 3.0 mm.
 5. The multilayer lightdiffuser plate of claim 1, wherein, the multilayer light diffuser plateis made by foam extrusion molding, and the main layer comprises aplurality of microbubbles and a plurality of diffusing particles; amaterial of the diffusing particles is one of the following: calciumcarbonate, silicon dioxide, titanium dioxide, silicone resinmicroparticles, and polymethyl methacrylate microparticles; a weightpercentage of the diffusing particles in the main layer is 0.1%-10%; themicrobubbles are distributed in the main layer; due to the difference inrefractive indices between air in the microbubbles and the material ofthe main layer, light traveling in the main layer can be refracted,reflected or scattered by the microbubbles; a weight reduction rate ofthe microbubbles to the main layer is 15-25%, and an average size of themicrobubbles is between 60˜800 μm; wherein, a calculation formula of theweight reduction rate is:weight reduction rate (%)=(W1−W2)/W2*100%;W1=H*(L1*L2*D); wherein: H is the average thickness of the main layer(mm); L1 is the length of the main layer (mm); L2 is the width of themain layer (mm); D is the density of the raw material of the main layer(g/mm³); W1 is the theoretical weight (g) of the main layer, that is,the weight when the microbubbles are not included; W2 is the actualweight (g) of the main layer, that is, the actual weight of the platebody containing a plurality of the microbubbles is actually weighed by ascale,
 6. (canceled)
 7. The multilayer light diffuser plate of claim 1,wherein: the microstructures include a plurality of N-sided pyramids,wherein N is a positive integer greater than or equal to three; t2 isbetween 6-200 μm; the maximum width of the convex portions is between50-500 μm; a distance between two adjacent said convex portions isbetween 50-1000 μm; a thickness of the water-blocking and gas-blockinglayer is t3, and t3 is between 5-100 μm; the blue light LED light sourcemodule is a sub-millimeter light-emitting diode (Mini LED) array modulecapable of emitting blue light; a wavelength of the blue light isbetween 430-500 nm.
 8. The multilayer light diffuser plate of claim 1,wherein, a plurality of said microstructures is disposed on thelight-incident surface of the multilayer light diffuser plate in anarray form; a plurality of said convex portions and a plurality of saidconcave portions are formed on the light-incident surface by means ofthe microstructures.
 9. A method for manufacturing a multilayer lightdiffuser plate, comprising the following steps: a step for insertingmaterial, wherein at least a first base material, a second basematerial, a foaming agent, and a plurality of diffusing particles areput into a foam extrusion molding machine from a feeding port; whereinthe first base material and the second base material have differentrefractive indices; a step for heating and kneading, wherein, in thefoam extrusion molding machine, the inserted materials are uniformlyheated, kneaded and foamed at a general processing temperature suitablefor polycarbonate; wherein the first base material and the second basematerial are separately heated and kneaded without mixing; a step fordistributing feed block, wherein, the heated and kneaded first basematerial and the heated and kneaded second base material are directed toa distributing feed block; by using the distributing feed block, theheated and kneaded first base material is split into a main layer and aplurality of first base material layers, and the heated and kneadedsecond base material is split into a plurality of second base materiallayers, and the first base material layers and the second base materiallayers are alternately stacked to form a partially-transmissive andpartially-reflective layer, and moreover, and the partially-transmissiveand partially-reflective layer is superimposed on the main layer; a stepfor T-Dies, wherein, through a T-die of the foam extrusion moldingmachine, the uniformly kneaded, foamed and superimposed main layer andthe partially-transmissive and partially-reflective layer from thedistributing feed block are co-extruded into a one-piece multilayerplastic plate; a step for rolling, wherein, the one-piece multilayerplastic plate is rolled and cooled through a roller module; and a stepfor output product, wherein the cooled one-piece multilayer plasticplate is sent out from a discharge port of the foam extrusion moldingmachine as a product of multilayer light diffuser plate; wherein themultilayer light diffuser plate sent out from the discharge port has alight-incident surface and a light-emitting surface that are parallel toeach other, and a thickness that is perpendicular to the light-incidentsurface and the light-emitting surface; in addition, the multilayerlight diffuser plate comprises the main layer and thepartially-transmissive and partially-reflective layer; thelight-emitting surface is located on a top surface of the main layer,the partially-transmissive and partially-reflective layer is locatedbelow the main layer, and the light-incident surface is located on abottom surface of the partially-transmissive and partially-reflectivelayer; wherein the partially-transmissive and partially-reflective layercomprises the first base material layers and the second base materiallayers stacked alternately; at least one of the upper and lower sides ofeach of the first base material layers is adjacent to one of the secondbase material layers; in addition, at least one of the upper and lowersides of each of the second base material layers is adjacent to one ofthe first base material layers; a material constituting the first basematerial layers and another material constituting the second basematerial layers have different refractive indices.
 10. The method formanufacturing a multilayer light diffuser plate of claim 9, wherein,base materials of the main layer and the partially-transmissive andpartially-reflective layer are either non-crystalline orsemi-crystalline plasticized materials; a ratio of the thickness of themain layer to the thickness of the partially-transmissive andpartially-reflective layer is in the range of 9:1 to 7:3; a number ofstacked layers of the partially-transmissive and partially-reflectivelayer, that is, the sum of the number of layers of the first basematerial layers and the second base material layers, is between 50 and400 layers; a ratio of the thickness of the first base material layer tothe thickness of the second base material layer is ranged from 3:1 to1:3.
 11. The method for manufacturing a multilayer light diffuser plateof claim 10, wherein, the materials of the main layer and thepartially-transmissive and partially-reflective layer are respectivelyselected from one of the following: polycarbonate (PC), polystyrene(PS), polymethyl methacrylate (PMMA, commonly known as acrylic force),polyethylene (PE), polypropylene (PP), and polyethylene terephthalate(PET); the number of stacked layers of the partially-transmissive andpartially-reflective layer is between 100 and 400 layers.
 12. The methodfor manufacturing a multilayer light diffuser plate of claim 11,wherein, the material of the main layer is polycarbonate (PC); thematerial of the first base material layers is polycarbonate (PC); thematerial of the second base material layers is polymethyl methacrylate(PMMA); the thicknesses of the first base material layer and thethicknesses of the second base material layer are the same, that is, theratio of the thickness of each first base material layer to thethickness of each second base material layer 122 is 1:1; the thicknessof the multilayer light diffuser plate ranges from 1.0 mm to 3.0 mm. 13.The method for manufacturing a multilayer light diffuser plate of claim10, wherein, the multilayer light diffuser plate is made by foamextrusion molding, and the main layer comprises a plurality ofmicrobubbles and a plurality of diffusing particles; a material of thediffusing particles is one of the following: calcium carbonate, silicondioxide, titanium dioxide, silicone resin microparticles, and polymethylmethacrylate microparticles; a weight percentage of the diffusingparticles in the main layer is 0.1%˜10%; the microbubbles aredistributed in the main layer; due to the difference in refractiveindices between air in the microbubbles and the material of the mainlayer, light traveling in the main layer can be refracted, reflected orscattered by the microbubbles; a weight reduction rate of themicrobubbles to the main layer is 15-25%, and an average size of themicrobubbles is between 60-800 μm; wherein, a calculation formula of theweight reduction rate is:weight reduction rate (%)=(W1−W2)/W2*100%;W1=H*(L1*L2*D); wherein: H is the average thickness of the main layer(mm); L1 is the length of the main layer (mm); L2 is the width of themain layer (mm); D is the density of the raw material of the main layer(g/mm³); W1 is the theoretical weight (g) of the main layer, that is,the weight when the microbubbles are not included; W2 is the actualweight (g) of the main layer, that is, the actual weight of the platebody containing a plurality of the microbubbles is actually weighed by ascale.
 14. The method for manufacturing a multilayer light diffuserplate of claim 10, wherein, in the step for rolling, the roller modulerolls on the one-piece multilayer plastic plate in order to form aplurality of microstructures on a light-emitting surface of theone-piece multilayer plastic plate, so that the microstructures arearranged on the light-emitting surface in an array form; themicrostructures form a plurality of convex portions and a plurality ofconcave portions on the light-emitting surface; the concave portions areseparated by the convex portions, so the concave portions areindependent and do not communicate with each other; wherein, thefollowing steps are further after the step for rolling: a step forcoating a quantum dot layer on the concave portions on thelight-emitting surface of the multilayer light diffuser plate by acoating process; a thickness of the quantum dot layer is t1, a distancefrom a top of the convex portions to a bottom of the concave portions ist2, wherein t1<t2; and a step for sticking a water-blocking andgas-blocking layer onto the light-emitting surface of the multilayerlight diffuser plate in order to cover the convex portions and thequantum dot layer; wherein, the quantum dot layer includes a pluralityof quantum dots (QD for short); the multilayer light diffuser plate isused with a blue light source module; the blue light source module is ablue light submillimeter light-emitting diode light source modulecomprises a plurality of blue light submillimeter light-emitting diodes(Mini LEDs) arranged in an array.
 15. The method for manufacturing amultilayer light diffuser plate of claim 14, wherein, the quantum dotsare nanocrystal semiconductor materials, which are composed of II-VI,III-V or IV-VI group elements; a grain diameter of each of the quantumdots is between 2 nm and 10 nm; wherein, the quantum dots include aplurality of green quantum dots with light emission wavelengths of520-530 nm and a plurality of red quantum dots with light emissionwavelengths of 620-630 nm; the microstructures include a plurality ofN-sided pyramids, wherein N is a positive integer greater than or equalto three; t2 is between 6-200 μpm; the maximum width of the convexportions is between 50-500 μm; a distance between two adjacent saidconvex portions is between 50-1000 μm; a thickness of the water-blockingand gas-blocking layer is t3, and t3 is between 5-100 μm; a wavelengthof the blue light emitted by the blue light Mini LEDs is between 430-500nm.
 16. The method for manufacturing a multilayer light diffuser plateof claim 14, wherein, a plurality of said microstructures is disposed onthe light-incident surface of the multilayer light diffuser plate in anarray form; a plurality of said convex portions and a plurality of saidconcave portions are formed on the light-incident surface by means ofthe microstructures.